The present invention relates to an internal combustion engine and is particularly concerned with the design of the engine block of large capacity engines as used in trucks and agricultural vehicles.
The gear train that drives the camshaft from the crankshaft in an internal combustion engine can be mounted either at the front end or the rear end of the engine. The rear of the engine refers to the end connected to the vehicle drive train, i.e. the end on which the flywheel and gearbox are mounted. From the point of view of reducing noise, the rear mounted drive train configuration is to be preferred but packaging considerations may dictate that the drive train be positioned at the front of the engine.
Heretofore, a manufacturer producing variants of the same engine having front and rear camshaft gear trains needed to produce two totally different engine blocks. This added to manufacturing costs.
The present invention provides an engine block having machined front and rear faces, wherein each of the front and rear faces is capable of receiving and sealing against a housing enclosing a gear train for coupling the engine crankshaft to a camshaft of the engine, and wherein the front face is additionally capable of directly mating with and sealing against an engine front cover and the rear face is additionally capable of directly mating with and sealing against a flywheel housing, whereby the same engine block may be selectively assembled into an engine having a front mounted or a rear mounted camshaft gear train.
As the size and shape of the drive train housing will usually differ from the size and shape of the engine front cover, or the flywheel housing, as the case may be, the front and rear faces of an engine block will have machined sealing surfaces and holes for receiving fastening elements that are redundant in any selected camshaft gear train configuration.
In the present invention, the same engine block can be sent to different assembly lines for the manufacture of engines having both front mounted and rear mounted gear trains. This results in a considerable cost saving, avoiding the need for separate castings for the different engine variants.
In order to be able to mount the gear or cog driving the camshaft at either end of the engine, it is important that there should be fastening elements provided at both ends of the engine to receive an axial thrust bearing plate to limit the axial displacement of the camshaft. It is possible to use these fastening elements at the front end of the engine to secure the front cover to the engine block when the camshaft gear train is mounted at the rear of the engine.
It is preferred to provide a water pump fastening element at the front end of the engine and to mount a belt driven water pump at the front end of the engine, regardless of the position of the camshaft gear train.
It is further preferred to provide fastening elements for mounting a gear driven oil pump at the front end of the engine to be driven from the front end of the engine crankshaft, regardless of the position of the camshaft gear train.
To facilitate the introduction of the camshaft into the engine block from either end of the engine and to enable the same camshaft to be used in both gear train configurations, it is preferred to provide bushed cam journals at both ends of the engine for supporting the camshaft.
It is also desirable to be able to reverse the oil pan and to this end it is advantageous to provide a symmetrical bolt pattern on the underside of the engine.
The camshaft gear train, in both engine configurations, may additionally include means for driving ancillary equipment, such as a mechanical fuel pump, a hydraulic pump or a power steering pump.